This invention relates to an automatic device for converting conventional vehicle tires into safety tires having special traction elements added to the conventional tires when increased traction is needed for snow, ice, or other slippery conditions.
It has long been known that vehicle tires with conventional tire treads designed for relatively smooth roads often do not provide adequate traction for snow, ice or other slippery conditions. Accordingly, it is customary for persons who will be driving in locations and at times where such conditions may be encountered either to equip their vehicles with so-called “snow tires ” having special deep treads for better traction or to carry with them so-called “snow chains” to be mounted on the tires when the slippery conditions are encountered. Both snow tires and snow chains typically are used only on the powered wheels of the vehicle. While snow tires are usable on non-slippery surfaces and thus can be conveniently used, where legal, for the entire snow season, chains provide a higher level of traction and are more effective.
Typical snow chains comprise a series of short lengths of flexible and durable material, usually metal but sometimes plastic or the like, spaced around and extending transversely across the tread of the tire, and two mounting strips that are connected to opposite ends of the transverse strips to extend along the sidewalls of the tire and joined together at their ends to secure the chains in place around the tires. Typically, a releasable clip carried on one end of the mounting strip is releasably connected to a link on the other end to secure the chain in place
Unfortunately, chains can be damaged by driving on “dry” pavement for more than brief periods, and also can damage tires and some road surfaces. Accordingly, chains cannot be left indefinitely on a vehicle during the snow season, but instead typically are carried in the vehicle and installed whenever the need arises and for as long as the need continues. A major disadvantage of such chains, however, is the time and effort required to install them on the tires, particularly when the need arises during a trip so as to require roadside installation. Moreover, such installation cannot be performed quickly or while the vehicle is in motion, so chains cannot be made immediately available in an emergency situation, such as the dangerous situation when a vehicle is driven unexpectedly onto a stretch of ice on the roadway. Every installation of conventional chains requires the user to stop the vehicle, position the chains on the respective wheels of the vehicle, and then connect the ends of the chains before resuming driving. This can be a nasty process in the cold, snowy or slushy conditions that often exist when the need for chains arises.
Efforts have been made to provide snow chains and similar devices that are more easily installed for use. For example, U.S. Pat. No. 5,501,482 discloses a traction device that can be fitted to the side of a wheel and having a number of generally radially extending traction arms formed integrally with a central disc and having free outer end portions that bend around the tire. As with conventional chains, this type of traction device must be installed manually on the wheels when snow conditions are encountered, and does not avoid the shortcomings of other prior devices. While some of these devices appear to be better than conventional snow chains, the need still exists for a safe, effective and reliable tire device that can be automatically installed on, and removed from, vehicle tires so as to be quickly and easily available when needed without the time delay and effort required for conventional snow chains and traction devices.